Roar in cab after dual exhaust installation.

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Rocky Veley

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Recently had dual exhaust installed and have roar in cab at certain speeds/rpm's. Truck had single exhaust w/flowmaster 40 when purchased in 2015. Now have 2 flowmaster 40's and have the roar. I have not had very much exhaust done in many years and wonder if this is to be expected?
Muffler shop said installing x pipe before mufflers would take some of it out. Had x pipe installed yesterday and that did not seem to take much of the roar out if any.
Hi. Had the same thing happen to an 84 C10. 6.2 diesel. 84 had tail pipes and x pipe. no luck. Ended up selling it. Found out later I need to install ' side branch resonators '. Just a 4' long pipe that dead ends on each side . Look it up. Something to do with sound waves. Cheers
 

MikeB

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Welcome to the drone of Flowmaster 40s. Even The "quieter" Delta Flow 50s do it.:( They are actually louder than many straight-thru mufflers that make more power.
 

78C10BigTen

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Welcome to the drone of Flowmaster 40s. Even The "quieter" Delta Flow 50s do it.:( They are actually louder than many straight-thru mufflers that make more power.
Ive had them on for 4 years... im used to them
 

82sbshortbed

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I've found a nice loud sound system gets rid of all drone sounds created by exhaust.
 

peats

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i suggest adding dynamat
 

ali_c20

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Add a short glasspack muffler before the flowmasters. This worked for me and killed the drone in all rpm ranges without taking to much sound out of the system.
 

Frankenchevy

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a crossover, decent mufflers and routing all the way out the back will make a big difference.
 

Preston

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I had the same issue with my 85 I was driving the truck and adding pipe a little at a time the last thing I did that worked was a 90 degree turn down just in front of the rear axel made all the drone go away still have the sound I wanted
 

sdewolfe

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Howdy,

Inspect the entire length of the exhaust for solidly mounted hangers. You are looking for two things; any direct metal to metal contact between the frame and the cab sheet metal, and any hanger welded solidly between the frame and exhaust. If the installer eliminated the rubber isolaters from the hangers the exhaust vibration will be transmitted directly into the frame. Now you have a tuned cavity (the cab) connected to long vibrating tubes. At resonant frequencies you will be inside a drum. Worn out cab isolators will exacerbate the problem. If the installer welded a strap to the cab, eliminate it entirely.
 

MikeB

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Add a short glasspack muffler before the flowmasters. This worked for me and killed the drone in all rpm ranges without taking to much sound out of the system.
I did that after the Delta Flow 50s I once had. Used 12" Summit Racing glass packs. Made a big difference.

I read later that with a 2-1/4" system, it's better to use 2-1/2" glass packs with adapters to reduce flow restriction.
 

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